#include <jni.h>
#include <android/log.h>
#include <string>
#include "md5.h"


/* forward declaration */
static void Transform(UINT4 *buf, UINT4 *in);

static unsigned char PADDING[64] = {
        0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

/* F, G, H and I are basic MD5 functions */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4 */
/* Rotation is separate from addition to prevent recomputation */
#define FF(a, b, c, d, x, s, ac) \
  {(a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) \
  {(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) \
  {(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) \
  {(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }

#ifdef __STDC__
#define UL(x)    x##U
#else
#define UL(x)	x
#endif

/* The routine MD5_Init initializes the message-digest context
   mdContext. All fields are set to zero.
 */
void MD5_Init(MD5_CTX *mdContext) {
    mdContext->i[0] = mdContext->i[1] = (UINT4) 0;

/* Load magic initialization constants.
 */
    mdContext->buf[0] = (UINT4) 0x67452301;
    mdContext->buf[1] = (UINT4) 0xefcdab89;
    mdContext->buf[2] = (UINT4) 0x98badcfe;
    mdContext->buf[3] = (UINT4) 0x10325476;
}

void MD5_Init2(MD5_CTX *mdContext) {
    mdContext->i[0] = mdContext->i[1] = (UINT4) 0;

    mdContext->buf[0] = (UINT4) 0xaa452301;
    mdContext->buf[1] = (UINT4) 0xbbcdab89;
    mdContext->buf[2] = (UINT4) 0xccbadcfe;
    mdContext->buf[3] = (UINT4) 0xdd325476;
}

/* The routine MD5Update updates the message-digest context to
   account for the presence of each of the characters inBuf[0..inLen-1]
   in the message whose digest is being computed.
 */
void MD5_Update(MD5_CTX *mdContext, const unsigned char *inBuf, unsigned int inLen) {
    UINT4 in[16];
    int mdi;
    unsigned int i, ii;

    /* compute number of bytes mod 64 */
    mdi = (int) ((mdContext->i[0] >> 3) & 0x3F);

    /* update number of bits */
    if ((mdContext->i[0] + ((UINT4) inLen << 3)) < mdContext->i[0])
        mdContext->i[1]++;
    mdContext->i[0] += ((UINT4) inLen << 3);
    mdContext->i[1] += ((UINT4) inLen >> 29);

    while (inLen--) {
    /* add new character to buffer, increment mdi */
        mdContext->in[mdi++] = *inBuf++;

    /* transform if necessary */
        if (mdi == 0x40) {
            for (i = 0, ii = 0; i < 16; i++, ii += 4)
                in[i] = (((UINT4) mdContext->in[ii + 3]) << 24) |
                        (((UINT4) mdContext->in[ii + 2]) << 16) |
                        (((UINT4) mdContext->in[ii + 1]) << 8) |
                        ((UINT4) mdContext->in[ii]);
            Transform(mdContext->buf, in);
            mdi = 0;
        }
    }
}

/* The routine MD5Final terminates the message-digest computation and
   ends with the desired message digest in mdContext->digest[0...15].
 */
void MD5_Final(unsigned char hash[], MD5_CTX *mdContext) {
    UINT4 in[16];
    int mdi;
    unsigned int i, ii;
    unsigned int padLen;

    /* save number of bits */
    in[14] = mdContext->i[0];
    in[15] = mdContext->i[1];

    /* compute number of bytes mod 64 */
    mdi = (int) ((mdContext->i[0] >> 3) & 0x3F);

    /* pad out to 56 mod 64 */
    padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
    MD5_Update(mdContext, PADDING, padLen);

    /* append length in bits and transform */
    for (i = 0, ii = 0; i < 14; i++, ii += 4)
        in[i] = (((UINT4) mdContext->in[ii + 3]) << 24) |
                (((UINT4) mdContext->in[ii + 2]) << 16) |
                (((UINT4) mdContext->in[ii + 1]) << 8) |
                ((UINT4) mdContext->in[ii]);
    Transform(mdContext->buf, in);

    /* store buffer in digest */
    for (i = 0, ii = 0; i < 4; i++, ii += 4) {
        mdContext->digest[ii] = (unsigned char) (mdContext->buf[i] & 0xFF);
        mdContext->digest[ii + 1] =
                (unsigned char) ((mdContext->buf[i] >> 8) & 0xFF);
        mdContext->digest[ii + 2] =
                (unsigned char) ((mdContext->buf[i] >> 16) & 0xFF);
        mdContext->digest[ii + 3] =
                (unsigned char) ((mdContext->buf[i] >> 24) & 0xFF);
    }
    memcpy(hash, mdContext->digest, 16);
}

/* Basic MD5 step. Transforms buf based on in.
 */
static void Transform(UINT4 *buf, UINT4 *in) {
    UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];


/* Round 1 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
    FF (a, b, c, d, in[0], S11, UL(3614090360)); /* 1 */
    FF (d, a, b, c, in[1], S12, UL(3905402710)); /* 2 */
    FF (c, d, a, b, in[2], S13, UL(606105819)); /* 3 */
    FF (b, c, d, a, in[3], S14, UL(3250441966)); /* 4 */
    FF (a, b, c, d, in[4], S11, UL(4118548399)); /* 5 */
    FF (d, a, b, c, in[5], S12, UL(1200080426)); /* 6 */
    FF (c, d, a, b, in[6], S13, UL(2821735955)); /* 7 */
    FF (b, c, d, a, in[7], S14, UL(4249261313)); /* 8 */
    FF (a, b, c, d, in[8], S11, UL(1770035416)); /* 9 */
    FF (d, a, b, c, in[9], S12, UL(2336552879)); /* 10 */
    FF (c, d, a, b, in[10], S13, UL(4294925233)); /* 11 */
    FF (b, c, d, a, in[11], S14, UL(2304563134)); /* 12 */
    FF (a, b, c, d, in[12], S11, UL(1804603682)); /* 13 */
    FF (d, a, b, c, in[13], S12, UL(4254626195)); /* 14 */
    FF (c, d, a, b, in[14], S13, UL(2792965006)); /* 15 */
    FF (b, c, d, a, in[15], S14, UL(1236535329)); /* 16 */

/* Round 2 */
#define S21 5
#define S22 9
#define S23 14
#define S24 20
    GG (a, b, c, d, in[1], S21, UL(4129170786)); /* 17 */
    GG (d, a, b, c, in[6], S22, UL(3225465664)); /* 18 */
    GG (c, d, a, b, in[11], S23, UL(643717713)); /* 19 */
    GG (b, c, d, a, in[0], S24, UL(3921069994)); /* 20 */
    GG (a, b, c, d, in[5], S21, UL(3593408605)); /* 21 */
    GG (d, a, b, c, in[10], S22, UL(38016083)); /* 22 */
    GG (c, d, a, b, in[15], S23, UL(3634488961)); /* 23 */
    GG (b, c, d, a, in[4], S24, UL(3889429448)); /* 24 */
    GG (a, b, c, d, in[9], S21, UL(568446438)); /* 25 */
    GG (d, a, b, c, in[14], S22, UL(3275163606)); /* 26 */
    GG (c, d, a, b, in[3], S23, UL(4107603335)); /* 27 */
    GG (b, c, d, a, in[8], S24, UL(1163531501)); /* 28 */
    GG (a, b, c, d, in[13], S21, UL(2850285829)); /* 29 */
    GG (d, a, b, c, in[2], S22, UL(4243563512)); /* 30 */
    GG (c, d, a, b, in[7], S23, UL(1735328473)); /* 31 */
    GG (b, c, d, a, in[12], S24, UL(2368359562)); /* 32 */

/* Round 3 */
#define S31 4
#define S32 11
#define S33 16
#define S34 23
    HH (a, b, c, d, in[5], S31, UL(4294588738)); /* 33 */
    HH (d, a, b, c, in[8], S32, UL(2272392833)); /* 34 */
    HH (c, d, a, b, in[11], S33, UL(1839030562)); /* 35 */
    HH (b, c, d, a, in[14], S34, UL(4259657740)); /* 36 */
    HH (a, b, c, d, in[1], S31, UL(2763975236)); /* 37 */
    HH (d, a, b, c, in[4], S32, UL(1272893353)); /* 38 */
    HH (c, d, a, b, in[7], S33, UL(4139469664)); /* 39 */
    HH (b, c, d, a, in[10], S34, UL(3200236656)); /* 40 */
    HH (a, b, c, d, in[13], S31, UL(681279174)); /* 41 */
    HH (d, a, b, c, in[0], S32, UL(3936430074)); /* 42 */
    HH (c, d, a, b, in[3], S33, UL(3572445317)); /* 43 */
    HH (b, c, d, a, in[6], S34, UL(76029189)); /* 44 */
    HH (a, b, c, d, in[9], S31, UL(3654602809)); /* 45 */
    HH (d, a, b, c, in[12], S32, UL(3873151461)); /* 46 */
    HH (c, d, a, b, in[15], S33, UL(530742520)); /* 47 */
    HH (b, c, d, a, in[2], S34, UL(3299628645)); /* 48 */

/* Round 4 */
#define S41 6
#define S42 10
#define S43 15
#define S44 21
    II (a, b, c, d, in[0], S41, UL(4096336452)); /* 49 */
    II (d, a, b, c, in[7], S42, UL(1126891415)); /* 50 */
    II (c, d, a, b, in[14], S43, UL(2878612391)); /* 51 */
    II (b, c, d, a, in[5], S44, UL(4237533241)); /* 52 */
    II (a, b, c, d, in[12], S41, UL(1700485571)); /* 53 */
    II (d, a, b, c, in[3], S42, UL(2399980690)); /* 54 */
    II (c, d, a, b, in[10], S43, UL(4293915773)); /* 55 */
    II (b, c, d, a, in[1], S44, UL(2240044497)); /* 56 */
    II (a, b, c, d, in[8], S41, UL(1873313359)); /* 57 */
    II (d, a, b, c, in[15], S42, UL(4264355552)); /* 58 */
    II (c, d, a, b, in[6], S43, UL(2734768916)); /* 59 */
    II (b, c, d, a, in[13], S44, UL(1309151649)); /* 60 */
    II (a, b, c, d, in[4], S41, UL(4149444226)); /* 61 */
    II (d, a, b, c, in[11], S42, UL(3174756917)); /* 62 */
    II (c, d, a, b, in[2], S43, UL(718787259)); /* 63 */
    II (b, c, d, a, in[9], S44, UL(3951481745)); /* 64 */

    buf[0] += a;
    buf[1] += b;
    buf[2] += c;
    buf[3] += d;
}

std::string bytesToHex(const uint8_t *bytes, size_t length) {
    char hexStr[33];
    for (size_t i = 0; i < length; i++) {
        sprintf(&hexStr[i * 2], "%02x", bytes[i]);
    }
    hexStr[32] = '\0';
    return hexStr;
}

extern "C"
JNIEXPORT jstring JNICALL
Java_com_cyrus_example_md5_MD5Utils_md5(JNIEnv *env, jclass, jstring input) {
    const char *inputChars = env->GetStringUTFChars(input, nullptr);
    if (!inputChars) return nullptr;

    MD5_CTX ctx;
    MD5_Init(&ctx);
    MD5_Update(&ctx, (unsigned char *) inputChars, strlen(inputChars));

    uint8_t digest[16];
    MD5_Final(digest, &ctx);
    env->ReleaseStringUTFChars(input, inputChars);

    std::string md5Hash = bytesToHex(digest, 16);
    return env->NewStringUTF(md5Hash.c_str());
}



extern "C"
JNIEXPORT jstring JNICALL
Java_com_cyrus_example_md5_MD5Utils_changeMD5Init(JNIEnv *env, jclass, jstring input) {
    const char *inputChars = env->GetStringUTFChars(input, nullptr);
    if (!inputChars) return nullptr;

    MD5_CTX ctx;
    MD5_Init2(&ctx);
    MD5_Update(&ctx, (unsigned char *) inputChars, strlen(inputChars));

    uint8_t digest[16];
    MD5_Final(digest, &ctx);
    env->ReleaseStringUTFChars(input, inputChars);

    std::string md5Hash = bytesToHex(digest, 16);
    return env->NewStringUTF(md5Hash.c_str());
}




extern "C"
JNIEXPORT jstring JNICALL
Java_com_cyrus_example_md5_MD5Utils_changeMD5Update(JNIEnv *env, jclass, jstring input) {
    const char *inputChars = env->GetStringUTFChars(input, nullptr);
    if (!inputChars) return nullptr;

    MD5_CTX ctx;
    MD5_Init(&ctx);
    MD5_Update(&ctx, (unsigned char *) "cyrus", strlen(inputChars));
    MD5_Update(&ctx, (unsigned char *) "studio", strlen(inputChars));
    MD5_Update(&ctx, (unsigned char *) inputChars, strlen(inputChars));

    uint8_t digest[16];
    MD5_Final(digest, &ctx);
    env->ReleaseStringUTFChars(input, inputChars);

    std::string md5Hash = bytesToHex(digest, 16);
    return env->NewStringUTF(md5Hash.c_str());
}


